nixon, would you like to comment on that statement >> i have no comment and in nixon's case, he percent spired. he had the audacity to per spire. as a consequence, the venue where you are where a debate goes on, it's like a meat locker. that's the reason. they negotiate how cold it's going to be because nobody wants to per spire because look what happened to nixon. it's amazing. >> schieffer: even a great communicator like franklin roosevelt knew the risk of debating. he was a heavy favorite to win re-election in 1940, so when republican wendell wilke demanded a debate, f.d.r. ignored him. he knew just appearing on the same stage with the president enhanced the stature of any challenger. >> i think that we both just just stand here >> reporter: it's hard to know where we'd be today if nixon in 1960 had followed roosevelt's lead. but once burned, nixon never debated again. nor did lyndon johnson who had preceded him to the white house. so there were no debates in 1964, '68 or '72. >> announcer: this is the cbs news special report. >> schieffer: only after his poll numbers dropped did ger